In recent years, switching of communication channels for packets by using a path protection scheme has been known in communication devices such as packet transmission devices. In the path protection scheme, upon detection of a failure in a regular communication channel through which a communication device transmits packets in a normal state, the path is switched to a backup communication channel provided as a backup for the regular communication channel.
In the path protection scheme, there are cases in which the communication device sets the priorities for the packets and performs transmission control corresponding to the priorities of the packets. For example, the communication device buffers, in queues, the packets corresponding to the priorities of the packets and sequentially transmits the packets from the queue in which the packets with high priority are stored.
For a communications network with a 1:1 configuration in which backup communication channels are provided for the respective regular communication channels on a one-to-one basis, the line cost increases. Hence, recent communications networks employ, for example, an N:1 configuration in which one backup communication channel is provided for multiple regular communication channels. For example, Japanese Unexamined Patent Application Publication No. 2003-258851 discloses a bath protection technology.